These stainless steel socket weld flanges are similar to a slip-on flange in outline, but the bore is counter - bored to accept pipe. The diameter of the remaining bore is the same as the inside diameter of the pipe. The stainless steel socket weld flanges are attached to the pipe by a fillet weld around the hub of the flange. An optional interval weld may be applied in high stress application. Socket weld flange's biggest use is in high pressure systems such as hydraulic and steam lines.